dispose method
Implementation
Future<void> dispose() async {
renderer.srcObject = null;
/// libwebrtc does not provide a way to clone MediaStreams. So stopping the
/// local stream here would break calls with all other participants if anyone
/// leaves. The local stream is manually disposed when user leaves. On web
/// streams are actually cloned.
if (!isGroupCall || isWeb) {
await stopMediaStream(stream);
}
stream = null;
await renderer.dispose();
}